Homoepitaxy Technology Based on the 4H-SiC Piezoresistor

Sun Yanan;Shi Yunbo;Feng Hengzhen;Wang Hua;Han Xingyu;Science and Technology on Electronic Test and Measurement Laboratory,North University of China;Key Laboratory of Instrumentation Science & Dynamic Measurement of Ministry of Education,North University of China;

The manufacturing technology of SiC-based MEMS piezoresistors was proposed in the experiment.High quality n-type and p-type homoepitaxial layers were grown on the off-axis1120 4H-SiC wafer with the diameter of 4 inches(1 inch=2.54 cm).The crystal quality,doping concentration and thickness of the epitaxial layers were tested and analyzed by the laser Raman spectroscopy,X-ray diffraction(XRD)and secondary ion mass spectroscopy(SIMS).Through comparing the Raman spectroscopy images of the substrate and epitaxial film after growing n-type homoepitaxial layer with the thickness of 2μm,it is concluded that the homoepitaxial layers well continue the crystal type of the substrate.The doping concentration of N element in the outermost n-type epitaxial layer was tested with the SIMS.And the result shows that the doping concentration of N element is uniform up to the medium level and the doping thickness is 1.98μm.The Raman test result of the doping concentration is in accordance with the experimental data of the SIMS.Finally,the maximum resistivity and minimum resistivity in the main area of the wafer were obtained by the four-probe method of the square resistance.The comparing results show that the radial inhomogeneity is 26.27%,indicating the good electrical property of the homoepitaxial layers.